One of the most amiable and least predictable of American directors, Austin-based indie Richard Linklater follows his deft period reconstruction “Me and Orson Welles” and animated Philip K. Dick yarn “A Scanner Darkly” with an exercise in regional humor. “Bernie” is a true-life Texas tall-tale about a murderous funeral director and the little town of Carthage that loved him.

The Ballad of Bernie Tiede is also a vehicle for Jack Black (who gave Linklater his career performance nine years ago in “School of Rock”). Introduced dressing and grooming a corpse for an audience of would-be morticians, Bernie is the town goody-goody — he literally puts the best face on death while taking it as his mission to comfort the newly bereaved. Elderly women are his specialty, but he nearly meets his match in the person of Carthage’s richest, meanest widow, and owner of the local bank, Marjorie Nugent.

Played by a poker-faced Shirley MacClaine (who doesn’t bother to feign an East Texas accent), Marjorie instantly rejects Bernie, but ultimately succumbs to his placid persistence. After winning her confidence (and power of attorney), escorting her on vacation trips to European spas and Broadway shows, enduring numerous temper tantrums, and performing all manner of humiliating chores, Bernie finally loses it. It’s practically a country-western ballad. The setting is not quite Bonnie and Clyde country (their Carthage was in Missouri) but close enough. He shoots her four times in the back then conceals her corpse in a freezer for nine months, using her money to the benefit of the town while pretending she’s in a hospital out of state.

Black’s Bernie is a study in bland ambiguity: Christian or con man, straight or gay, gigolo or caretaker, unbelievably sincere or brilliantly duplicitous, hymn-singing hypocrite or scheming Samaritan, Robin Hood or Jack the Ripper? To add to the confusion, Black gets to sing, dance (his “Seventy Six Trombones” is a virtual audition tape) and blubber like a baby. Linklater is less interested in his hero’s psychology than that of the town. Just about everyone hated Marjorie and loved Bernie. His trial has to be moved to a hamlet two counties away because the showboat district attorney Danny Buck Davidson (ripely played by Texas native Matthew McConaughey) knows that despite Bernie’s tearful confession, he’ll never get a conviction — especially since, at least in the movie, one of his most damning lines of questioning concerns the alleged killer’s knowledge of the appropriate wine to serve with fish.

Repetitive but not tiresome, Bernie is shot as a mock documentary — with the action annotated or described by a chorus of gossipy townspeople, many of them played by Bernie’s actual neighbors. This colorful discourse makes for the movie’s richest element. “That old heifer turned down loans just for a hobby,” says one of Marjorie. “They had more tattoos than teeth,” is how another characterizes the jury that heard Bernie’s case. The material brings Linklater near the realm of the Coen brothers; the methodology, as well as the material, takes him even closer to the world of documentarian Errol Morris. Herein lies a paradox. The bilious Coens would typically have treated the Passion of Bernie as a subject for grotesque farce; the habitually facetious Morris could have brought a ruthless defamiliarization to bear on the setting. Linklater’s attitude is none at all. Familiarity breeds no contempt, and consequently, “Bernie” lacks the edge of malice one might reasonably expect from so nasty a tale.